Rotary movements are measured with rotation angle sensors. A rotation angle sensor that supplies an output voltage which corresponding to the assumed rotary angle is known from WO 95 14 911 A. It consists of a stationary formation and of a rotating formation. The stationary formation includes two semi-circular shaped stator elements with a spacing opening between them and a Hall element located in said opening. The rotating formation exhibits a magnet element designed in a ring shape, which is supported by a support element and can be moved around the stator element while maintaining an air gap.
Such a rotation angle sensor is also known to the applicant from WO 98 25 102 A1, DE 197 16 985 A1, DE 199 03 490 A1 or EP 1 024 267 A2.
These embodiments of the rotation angle sensor have proven themselves. However, they require accurate adjustments. One adjustment option of the output values for the known sensors is presented in WO 98 22 781 A1. The advantage of this adjustment is that the output values can be adjusted to output voltages when the sensor is already encapsulated. In addition, the adjustments can be repeated any number of times.
A device for determining the position of rotating shafts is known from DE 197 16 985 A1. The Hall voltage generated by the movement of the rotor through the Hall IC elements that are located in two adjacent air gaps is provided to an evaluation unit, which generates from it an output voltage, where an output signal is assigned to each position angle between 0° and 360°.
The measurement of the degree of actuation of damper flaps or accelerator pedals is also possible using sensors according to the resistance method.
The use of a dual potentiometer for this purpose that provides output voltages of differing slopes is known from EP 0 457 033 B1.
Its disadvantage is that the resistance values change due to the operating temperatures that occur in the motor compartment, which leads to inaccurate readings.
It is known from DE 40 04 085 A1 to generate two output curves with slopes in opposite directions corresponding to the position change of the damper flap or the accelerator pedal using a dual potentiometer.
However, the required error indications cannot be carried out with the output curves due to the significantly fluctuating resistance values caused by the high operating temperatures in the motor compartment.
DE 38 20 475 C1 discloses a magnetic field sensor with a thin ferro-magnetic layer, and associated current and voltage contacts for reading out magnetically stored data. Adjacent ferro-magnetic layers are provided via an interim layer. Said ferromagnetic layers are made of materials that, without the contribution of an outer magnetic field, the magnetization of the one ferro-magnetic layer is oriented anti-parallel to the abutting or adjacent ferro-magnetic layer. The interim layer is made of a non-magnetic metal. With the known magnetic field sensor, the changes of the magnetic resistance, and thus the measurement signal, should be greater than with the magnetic field sensors known thus far. The solution for this is that the interim layer exhibits a thickness that is below the mean free path of the electrons.
A magnetic sensor for providing electric signals is known from DE 36 39 208 A1. As described therein, several resistors arranged at 90° to one another are located on a substrate. The sensor is moved relative to a permanent magnet in the homogenous magnetic field of the latter.
A device with a motion transducer element that includes a Wheatstone bridge containing two magnet-sensitive half bridges is known from EP 1 089 056 A1. It provides a simple determination of the direction of rotation of the motion transducer element.
A linear sensor operating according to the magneto-resistive principle, using a bridge circuit, as well is known from EP 1 046 021 A1 and EP 1 046 022 A1.
A rotation angle measuring device with a magneto-resistive sensor is known from Philips Semiconductors, General part 2, November 1994, P. 141-143. It can measure angles of up to 90°. However, the output voltage is susceptible to temperature changes.
Giant Magnetic Resistor (GMR) cells are also known. If these cells are exposed to a magnetic field, they deliver two delivery voltages that are positioned in a V-shape to one another. However, the GMR cells are used only as switches or as reader heads for hard disks.